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LF: Re: BPSK Tests

To: [email protected]
Subject: LF: Re: BPSK Tests
From: "Andrew Talbot" <G4J[email protected]>
Date: Thu, 28 Dec 2000 10:50:11 -0000
Reply-to: [email protected]
Sender: <[email protected]>
Yes, it was me for about an hour.  Just another soak test as I've finally
put IRF452 devices into the PA to give that extra bit of reliability now.
As the garden has dried out the antenna tuning has changed and I noticed the
PA heatsink getting quite a bit hotter than before whenon air testing.

Need to think carefully why dissipation increases so much on a reactive
load for a given supply current.  The transmitter is a voltage source with a
small internal resistance - 2 to 3 ohms is my estimate so I need to sit down
with phasor diagrams and a calculator to get a handle on this dissipation
issue.

It really is worth installing Coherent / Africa - the BPSK mode is an
excellent implementation with enough user flexibility to allow serious
experimentation.   I have given it a write up in the 'Data' column in
February's RadCom - in fact given the whole column over to it.

I'll put up the SMTH Hell signal now - at 1100z

Andy  G4JNT

-----Original Message-----
From: [email protected] <[email protected]>
To: [email protected] <[email protected]>
Date: 28 December 2000 01:28
Subject: LF: BPSK Tests


Hi Andy,

yesterday around 11:00 there was a 10 Hz wide patterned strip visible on
Spectrogram 137.790 kHz which looked like a BPSK transmission from you.
With
about -3 dBuV/m, the spectral density was 8 dB above the noise, but I
couldn't decode it yet as I haven't installed Bills software. It's the
first
time I have seen one of your sigs (new PA paying off ?), and I would really
like to look at your MT Hell one day.

Cheers de Markus,
DF6NM in JN59NK




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